Comprehensive Description

Description

Upright flattened branch with two or three short side projections (Fig. 26A), with wider base and a cut-off upper ending, possibly the specimen is only a fragment as base and apex look damaged. Length of holotype 6.5 cm, diameter 1.5 cm at the base, 1 cm higher up. Side projections only on one side of the branch, less than 1 cm long and 0.5 cm thick, with rounded apex. Surface uneven, somewhat hispid. No apparent oscules. Consistency firm. Colour (alcohol) red-brown. Skeleton: a dense mass of polyactines, towards the periphery surrounding long thin styles and short thin styles, which are embedded in the skeleton more so than in other Trikentrion species. No oxeas present, but T-shaped polyactines with very short basal clade appear to have taken the position of oxeas. Spicules: long thin styles, short thin styles, polyactines, trichodragmas. Long thin styles (Fig. 26B), smooth, straight, usually broken, so only a small number (five) were available for length measurements, 295–870.4–1394 × 9–14.6–24 µm. Short thin styles (Fig. 26C, C1), straight or gradually curved, 192–241.1–358 × 2–2.3–3 µm. Polyactines (Fig. 26D), basically three-claded, with the basal clade provided with strong conical spines near the apex. Two major morphological types appear dominant, those with almost equiangular outline (Fig. 26D1), and T-shaped forms with very short basal clade (Fig. 26D2), which is occasionally entirely smooth; basal cladi 27–51.3–96 × 11–13.7–21 µm, lateral cladi 33–96.3–121 × 9–13.9–19 µm. Trichodragmas (Figs 26E, E1), straight or sometimes curved sinuously, up to 50 or more individual raphides with apical spines, 49–54.4–61 × 5–7.7–11 µm.